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July 28, 2005

U.S.: NASA Grounds Shuttle Due To Falling Debris

The "Discovery" approaching the International Space Station today

NASA has announced the grounding of its space-shuttle fleet after large pieces of insulating foam broke off the external fuel tank of the shuttle "Discovery" during its launch this week. The incident was hauntingly similar to the problem that doomed the "Columbia" 2 1/2 years ago. The U.S. space agency says the seven "Discovery" astronauts are not in danger, as the debris does not seem to have damaged the ship.
Prague, 28 July 2005 -- The flight of the "Discovery" was NASA's first manned mission since the "Columbia" tragedy and was to be the first of two to test the new safety upgrades.

But all bets -- and future flights -- are now off until NASA resolves the recurring problem of falling debris during blastoff, as shuttle program manager Bill Parsons told reporters yesterday at the Johnson Space Center in Houston, Texas.

"Obviously, with the event that we've had, we were wrong," Parsons said. "We had put in place ways to observe this, we were looking for any kind of event like this, we did not expect the PAL ramp (hand-applied foam insulating the point where the tank and the orbiter connect) to have the issue that it had but it did. So what that causes for us is a step back and take a look.”

NASA had waited 2 1/2 years -- and spent 1 billion dollars improving the fuel tank and other safety measures -- to correct the problem that doomed the "Columbia" and its seven-member crew.

On 16 January 2003, a 0.75-kilogram piece of foam insulation broke off "Columbia"'s external tank during launch, gouging a hole in the ship's wing. Sixteen days later, as the shuttle attempted to reenter Earth’s atmosphere, superheated gases pierced the breach and tore the ship apart.

NASA was confident when the "Discovery" blasted off on 26 July that the problem with falling debris had mostly been resolved. But images of the shuttle’s external fuel tank, which is jettisoned just before orbit, later showed that chunks of insulation foam had come off in at least three areas during blastoff.

“We can't engineer anything to perfection," said Paul Hill, the shuttle’s flight director. "So, I expected we would shed some small, but tolerable amount of debris.”


Parsons said the largest of the three missing chunks of foam was about the same size as the one that struck "Columbia," but added: "The video clearly shows that it fell away and did not strike the orbiter."

He said NASA officials believe the seven astronauts aboard "Discovery" are not in any danger and will be safe to return to Earth on 7 August, as scheduled.

“There are some good things that came out of this -- the fact is it didn't cause any damage to the orbiter that we're aware of at this particular time; it looks like it did not contact the orbiter at all," Parsons said. "But it does cause us to pause, take a step back and take a look at what we might have to do."

Engineers are also looking at two areas on the shuttle's belly where tiny pieces of the ship's heat-resistant tile are missing.

"Discovery" docked at the International Space Station (ISS) today, and is to deliver critical supplies and practice heat-shield repair techniques during a series of space walks.

Another shuttle, "Atlantis," had been scheduled to launch for the next mission in September to resume construction of the ISS. But that flight, and all others, are now on hold indefinitely.

The grounding adds to the burden on the space station, which has been relying on smaller Russian spacecraft for crew and cargo deliveries.

NASA, which plans to retire its three shuttles in 2010, is at work on a new spacecraft.

(agencies)
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